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Prion-inducing domain 2-114 of yeast Sup35 protein transforms in vitro into amyloid-like filaments

C Y King1, P Tittmann, H Gross

  • 1Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule, CH-8093 Zürich, Switzerland.

Proceedings of the National Academy of Sciences of the United States of America
|June 24, 1997
PubMed

Insights

The yeast [PSI] factor, an abnormal Sup35 protein isoform, forms amyloid-like filaments. Seeding of these filaments may explain how the [PSI] factor is maintained in cells.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Yeast Genetics

Background:

  • The yeast non-Mendelian genetic factor [PSI] enhances tRNA-mediated nonsense suppression.
  • It is associated with an abnormal cellular isoform of the Sup35 protein.
  • The N-terminal region of Sup35p is crucial for [PSI] genesis and maintenance.

Purpose of the Study:

  • To investigate the in vitro aggregation properties of the Sup35 N-terminal fragment.
  • To determine if the Sup35 N-terminal fragment forms amyloid-like structures.
  • To explore the potential role of seeding in the maintenance of the [PSI] factor.

Main Methods:

  • In vitro aggregation assays of the Sup35 N-terminal fragment (Sup35pN).
  • Circular dichroism spectroscopy to analyze secondary structure.
  • Protease resistance assays.
  • Amyloid-like property assessment.
  • Seeding experiments to induce filament growth.

Main Results:

  • Sup35pN spontaneously forms thin filaments in vitro.
  • These filaments exhibit beta-sheet structure, increased protease resistance, and amyloid-like optical properties.
  • Filament formation can be seeded by preformed aggregates, promoting further growth.

Conclusions:

  • The abnormal cellular isoform of Sup35p associated with the [PSI] factor is likely an amyloid-like aggregate.
  • Seeding of Sup35p aggregates may be the mechanism responsible for maintaining the [PSI] element in vivo.

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